So far we looked at the polite forms of the い and な adjectives. Today we’ll look at the casual forms of い and な adjectives, but only in the present tense.

The present tense polite affirmative of an い adjective :

すずしいいです (cool)

The present tense casual affirmative of an い adjective :

すずしいい (cool)

To form the casual form of the present tense affirmative of an い adjective, just leave off the です.

The present tense polite affirmative of a な adjective :

あんぜんです (safe)

The present tense casual affirmative of a な adjective :

あんぜんだ (safe)

To form the casual affirmative of a な adjective, leave off the です and place だ in its place.

The present tense negative polite of an い adjective :

すずしくありません (not cool)

The present tense negative in the casual form of an い adjective :

すずしくない (not cool)

To form the present tense negative of an い adjective in the casual form, drop the ending ありません and attach ない to すずしく.

The present tense negative polite of a な adjective :

あんぜんじゃありません (not safe)

The present tense negative casual of a な adjective :

あんせんじゃない (not safe)

To form the present tense negative of a な adjective in the casual form, drop the ありません and replace it with ない.